Background: Obesity is the ultimate result of an imbalance between energy intake and energy expenditure. Currently, research has been focusing on specific food ingredients, which may have favorable effects on human metabolism and especially fat kinetics during exercise. Therefore, the purpose of this study was to examine the efficacy of a commercially available 'fat-burner' (Thermobol), containing a mixture of some of the aforementioned thermogenic ingredients, as well as a commercially available fish protein hydrolysate (Nutripeptin TM), on enhancing fat metabolism during submaximal exercise, at the intensity which elicits maximal fat oxidation rates (Fat max). Methods: In a randomized, double-blind crossover study design, 7 obese (BMI>30kg m-2), male participants completed a graded treadmill-exercise preliminary testing, followed by three experimental trials. The trials consisted of 60-min treadmill task corresponding to the Fat max intensity (speed and incline gradient), determined by the preliminary testing. Four hours and ½hours before the trials, the participants ingested 3 capsules of placebo, 3 tablets of Thermobol, or 6 capsules of Nutripeptin TM. Results: During the three experimental trials, the absolute fat (gmin-1) and carbohydrate (gmin-1) oxidation rates did not differ significantly between the three supplements. Energy expenditure (kcalmin-1) was significantly higher in the Thermobol supplement, compared to placebo [mean (S.D); 8.03 (1.46) Vs 8.24 (1.39); p=.042)], whereas in the Nutripeptin TM supplement, it was not (8.21 (1.46) Vs 8.0 (1.46); p=.073). Heart rate (bpm), RPE, blood glucose (mmol L-1) and blood lactate (mmol L-1) responses were not found to be significantly different across the three experimental conditions. Conclusion: Although Thermobol appeared to influence metabolism during submaximal exercise at the Fatmax intensity, Nutripeptin TM did not provide any metabolic effect.